A structural adhesive is used for bonding metal members, etc. in various fields such as the field of automobile and vehicle industry, the field of shipping industry, the field of aerospace industry and the field of civil engineering and construction industry. As the structural adhesive, a curable epoxy adhesive having an epoxy resin as the main component modified or blended with an elastomer or the like is widely used in the above fields. However, if the bonded portion is heated and exposed to a high temperature due to conditions for use, a conventional curable epoxy adhesive is insufficient in heat resistance. Thus, it has been studied to improve heat resistance of a curable epoxy adhesive (for example, Patent Document 1).
Further, although a fluorinated polymer is known as a resin excellent in heat resistance, in general it is difficult to obtain a sufficient adhesive property. Regarding this problem, a technique to improve adhesive property of a fluorinated polymer so as to be used for an adhesive is known (for example, Patent Document 2).
On the other hand, it is known that a cured product can be formed by copolymerizing tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, a perfluoro alkyl vinyl ether, etc. in the presence of a perfluoroalkyl diiodide to obtain a polymer having iodine atoms bonded to both terminals, followed by peroxide crosslinking with a triallyl isocyanurate or the like (for example, Patent Document 3).